World Library  
Flag as Inappropriate
Email this Article

Perkinsus marinus

Article Id: WHEBN0001686072
Reproduction Date:

Title: Perkinsus marinus  
Author: World Heritage Encyclopedia
Language: English
Subject: Perkinsus, Myzozoa, Alveolata, Alveolate, Apicomplexa
Publisher: World Heritage Encyclopedia

Perkinsus marinus

Perkinsus marinus
Scientific classification
Domain: Eukaryota
Kingdom: Chromalveolata
Superphylum: Alveolata
Phylum: Perkinsozoa
Class: Perkinsea
Order: Perkinsida
Family: Perkinsidae
Genus: Perkinsus
Species: P. marinus
Binomial name
Perkinsus marinus
(Mackin, Owen & Collier) Levine 1978
  • Labyrinthomyxa marina
  • Dermocystidium marinum

Perkinsus marinus is a species of protist belonging to the phylum Perkinsozoa.[1] It is similar to a dinoflagellate.[1][2] It is known as a prevalent pathogen of oysters, causing massive mortality in oyster populations. The disease it causes is known as dermo or perkinsosis, and is characterized by the degradation of oyster tissues.[3] The genome of this species has been sequenced.[4]


  • Taxonomy 1
  • Description and life cycle 2
  • Pathology 3
  • Distribution 4
  • Management 5
  • See also 6
  • References 7
  • Further reading 8


P. marinus is a protozoan of the protist superphylum Alveolata, the alveolates. Its phylum, Perkinsozoa, is a relatively new taxon positioned between the dinoflagellates and the Apicomplexa, and is probably more closely related to the former.[3] P. marinus is the type species of the genus Perkinsus, which was erected in 1978. When first identified in 1950, it was mistaken for a fungus.[5]

Description and life cycle

The protist is about 2 to 4 micrometers long.[6] The zoospore has two flagella which it uses to swim in its marine habitat. It is ingested by its mollusc host, which is often an oyster of the genus Crassostrea. It then becomes a trophozoite, which proliferates in the tissues of the host. P. marinus often infests the hemocytes, cells in the blood of the host.[7] It is also often seen in the cells of the intestine, connective tissues, digestive glands, and gills.[3] Inside the cell, the trophozoite produces a vacuole which displaces the cell nucleus. The infested cell is referred to as a signet ring cell, because it is spherical and filled with the rounded vacuole, and resembles a signet ring. The mature trophozoite undergoes binary fission and up to 16 immature trophozoites are produced. These stay in the host animal and infest its tissues, or are released into the water in the feces or from a dead host. Trophozoites in the water mature and release flagellated zoospores.[7]

The most economically important host is the eastern oyster (Crassostrea virginica). The parasite is also common in C. corteziensis, and the species C. rhizophorae, C. gasar, and C. brasiliana are probably susceptible. C. gigas and C. ariakensis are experimentally susceptible, but may be more resistant. Certain clams such as Mya arenaria and Macoma balthica can be infected in experimental situations. In the laboratory the sea snail Boonea impressa can be infected and then pass the parasite to an oyster host.[3]

Oyster anatomy


Perkinsosis, or dermo, is the disease condition of the oyster. The name "dermo" was coined when the protist was named Dermocystidium marinum, and it is still commonly used.[6] Infested cells are destroyed by the reproducing protist, and many trophozoites are released into the tissues of the host, or into its bloodstream. There they infest more cells or are excreted or released when the host dies and disintegrates. The infected oyster becomes stressed, its tissues pale in color, its gamete production is retarded, its growth slows, it becomes emaciated, its mantle shrivels and pulls away from the shell, and it may develop pockets of pus-like fluid.[3] Lysis of tissues and blockage of blood vessels causes fatality, but many oysters can persist up to three years with active infections.[6]


The protist occurs along the North American coast from Maine to Florida to the Yucatán Peninsula of Mexico. Dermo epizootic outbreaks occurred in the Gulf of Mexico in the 1940s. Periodic outbreaks in the Chesapeake Bay have caused extensive oyster mortality. Significant disease has occurred in Delaware Bay, Long Island Sound, and other parts of the coast of the northeastern United States.[6]

Oyster farming operations have been disrupted in some areas, particularly in Mexico.[3]


The prevalence of the protist and the disease are influenced by environmental factors such as temperature, salinity, and food availability to the host. Oysters exposed to environmental pollutants such as N-Nitrosodimethylamine and tributyltins experience more severe disease.[3] At higher temperatures, the chemical defenses of the oyster, particularly its lysozymes, are reduced; infections are more common and more severe in the summer.[8] Warmer winter ocean temperatures also promote outbreaks.[9]

While laboratory studies of certain antibiotics have been promising, there are no effective methods of eradication, so prevention is important. Oysters from populations or farms that have experienced disease should not be moved to areas without infestations, because the protist is easily introduced and transmitted. In aquaculture, there are efforts to locate and breed more resistant strains of oysters.[3] Infested seed oysters should not be planted in oyster beds, and in disease-ridden areas the oysters should be removed and the site allowed to lie fallow to reduce the protist load.[6]

See also


  1. ^ a b Joseph, S., et al. (2010). : biological insights from EST gene discovery.Perkinsus marinusThe alveolate BMC Genomics 11(1), 228.
  2. ^ Saldarriaga, J. F., et al. (2003). are early branches of the dinoflagellate lineage.Perkinsus marinus and Oxyrrhis marinaMultiple protein phylogenies show that International Journal of Systematic and Evolutionary Microbiology 53(1), 355-65.
  3. ^ a b c d e f g h Bower, S. M. ("dermo" disease) of oysters.Perkinsus marinusSynopsis of infectious diseases and parasites of commercially exploited shellfish: Fisheries and Oceans Canada. 2011.
  4. ^ Genome Report.Perkinsus marinus National Center for Biotechnology Information.
  5. ^ Villalba, A., et al. (2004). Perkinsosis in molluscs: a review. Aquatic Living Resources 17(04), 411-32.
  6. ^ a b c d e Sunila, I. Dermo Disease. Oyster and Clam Diseases. Connecticut Department of Agriculture.
  7. ^ a b Petty, D. Infections of Bivalve Molluscs.Perkinsus FA178. Fisheries and Aquatic Sciences. Florida Cooperative Extension Service. University of Florida IFAS. Published 2010.
  8. ^ Chu, F. L. E. and J. F. La Peyre. (1993). : temperature effects.Crassostrea virginica susceptibility and defense-related activities in eastern oysters Perkinsus marinus Diseases of Aquatic Organisms 16, 223-34.
  9. ^ Cook, T., et al. (1998). (dermo) disease epizootics in oysters.Perkinsus marinusThe relationship between increasing sea-surface temperature and the northward spread of Estuarine, Coastal and Shelf Science 46(4), 587-97.

Further reading

  • Audemard, C., et al. (2004). in environmental waters.Perkinsus marinusReal-time PCR for detection and quantification of the protistan parasite Applied and Environmental Microbiology 70(11), 6611-18.
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.

Copyright © World Library Foundation. All rights reserved. eBooks from Hawaii eBook Library are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.